Pass, no idea. There is a valid court ruling saying that you are entitled to sell individual games and Steam cannot stop you from doing so, ie their EULA is invalid in this regard.

But I am not aware about any legislation which would force them to create a mechanism for you to do so.

I guess it is easier with GoG games, you can just copy them to someone else’s pc, delete from your machine and it is sorted, someone else can use them.